Lithium ion batteries generate more energy than other types of batteries, which is why Boeing chose to use them. But they tend to overheat, causing "thermal events" — like fires — according to Rick Newman at US News.

University of Dayton professor Raul Ordonez told CNN, "These kinds of batteries are slightly more likely to cause problems."

Dr. Eric Stuve, a professor of chemical engineering at the University of Washington, told Wired, "These batteries have flammable components, that it well known."

In an airline industry that is struggling to make profits in the face of rising fuel costs, the promise of improved fuel efficiency is the biggest selling point of the Dreamliner,

The big question now is whether the battery troubles are a result of flawed design or manufacturing. A fault in the manufacturing process would be relatively easy to repair.

But if the design of the aircraft is flawed, Boeing would have to go back and make fundamental changes in how the plane is built, likely at a huge cost.